This invention relates to a catalyst, a method of making a catalyst and a process for making a hydrocarbon product having a low sulfur concentration. The invention further relates to a highly stable catalyst that is useful in the hydrodesulfurization of a heavy hydrocarbon feedstock, a method of making a highly stable catalyst for use in the hydrodesulfurization of a heavy hydrocarbon feedstock, and a process for the hydrodesulfurization of a heavy hydrocarbon product.
One process that is recognized by those skilled in the art of hydrocarbon hydroprocessing is the hydroconversion of heavy hydrocarbon feedstocks that contain hydrocarbons boiling above about 538° C. (1000° F.) so as to convert a portion of the heavy hydrocarbons into lighter hydrocarbons. It may also be desirable to simultaneously provide for the reduction of the sulfur content of such heavy hydrocarbon feedstocks. Many of the conventional catalysts used to provide for the hydroconversion and desulfurization of heavy hydrocarbon feedstocks contain a Group VIB metal component, such as molybdenum, and a Group VIII metal component, such as cobalt or nickel, supported on a refractory oxide support.
U.S. Pat. No. 5,827,421 (Sherwood, Jr) discloses a process for the hydroconversion and desulfurization of a heavy hydrocarbon feedstock using an alumina supported catalyst containing Group VIII and Group VIB metals and having specifically defined surface and pore characteristics. In its background section, this patent provides an extensive review and discussion of the prior art and the therein described catalysts used in the hydroconversion of heavy hydrocarbon feedstocks such as petroleum resid and other heavy hydrocarbons. This patent does not, however, provide any detail on the use of molybdenum trioxide as a necessary source of the molybdenum component of a hydroprocessing catalyst composition that is made by a method that includes the co-mulling of the molybdenum trioxide with an inorganic oxide material and a nickel compound.
U.S. Pat. No. 5,686,375 (Iyer et al.) mentions hydroprocessing catalysts that contain underbedded Group VIII metal components with the preferred catalyst comprising underbedded nickel and an overlayer of molybdenum. The patent states that many nickel and molybdenum compounds are useful for impregnation or comulling including precursors of molybdenum trioxide, but it does not specifically mention the comulling of molybdenum trioxide with the porous refractory support material in the preparation of its catalyst support that has an underbedded molybdenum component. The patent does, however, mention the incorporation of molybdenum onto the support that contains underbedded nickel by comulling instead of by impregnation. But, there is no teaching in the '375 patent of the preparation of a heavy hydrocarbon hydroconversion catalyst by the comulling of an inorganic support material with both molybdenum trioxide and a nickel compound followed by the resulting mixture being calcined to thereby form a catalyst material.
U.S. Pat. No. 6,030,915 (de Boer) discloses a hydroprocessing catalyst that uses regenerated spent hydroprocessing catalyst fines in the manufacture of a hydroprocessing catalyst. The patent further indicates that additional hydrogenation metals may be added to the catalyst composition by impregnation using an impregnation solution comprising water soluble salts of the hydrogenation metals to be incorporated into the catalyst composition. Also, an alternative method of incorporating the extra metal into the catalyst composition is indicated as including the mixing of either solid state or dissolved metal components with the mixture of regenerated spent hydroprocessing catalyst fines, binder, and, optionally, additive. The solid state metal may include solid molybdenum oxide. Additives are not indicated as being a catalytic metal compound. In the preparation of its catalyst, the '915 patent requires the regenerated spent hydroprocessing catalyst fines to be mixed with at least one additive, which may include a binder, such as alumina, silica, silica-alumina, titania and clays.